1. Field of the Invention
The present invention relates to an exhaust heat recovery control device that controls an exhaust heat recoverer recovering exhaust heat of an exhaust pipe or the like.
2. Description of Related Art
In an exhaust heat recoverer recovering exhaust heat from an exhaust pipe or the like, condensed water may be produced by recovering exhaust heat and thus cooling exhaust gas. The condensed water may cause damage to a catalyst unit for purifying exhaust gas, a switching valve for switching a flow channel of exhaust gas to an exhaust heat recoverer, and the like.
Therefore, Japanese Patent Application Publication No. 2006-161593 (JP 2006-161593 A) proposes an exhaust heat recovery system that prevents condensed water from coming into contact with a catalyst unit, a switching valve, or the like.
Specifically, in the exhaust heat recovery system described in JP 2006-161593 A, a heat exchanger for exhaust heat recovery is arranged in parallel with an exhaust pipe between a branched pipe branched from the exhaust pipe and a merged pipe merging on the downstream side of the branched part of the exhaust pipe. A flow channel switching valve switching a flow channel of exhaust gas to the exhaust pipe or the heat exchanger for exhaust heat recovery is disposed between the branched part and the merged part of the exhaust pipe. A part including a region between the flow channel switching valve and the merged part in the exhaust pipe is provided with a liquid storage part in which liquid can be stored.
However, in an environment below the freezing point, there is a possibility that condensed water produced in the exhaust heat recoverer will be frozen in the exhaust pipe. When the freezing in the exhaust pipe is not released but is kept in some traveling conditions and condensed water is further produced and frozen, the decrease in output power of an engine or the degradation in interior noise due to exhaust sound (also referred to as degradation in noise and vibration (NV) performance) may be caused, which provides room for improvement.